Thermal wraps or packs are commonly used to treat various injuries and ailments. For instance, cold packs, which typically decrease blood flow, are often used to reduce swelling and pain. Hot packs, which typically increase blood flow, are often used to warm muscles or reduce cramping. Conventional hot and cold packs are generally of two types: those that require external heating or cooling, and “chemical packs” that mix two or more reactants to cause an endothermic or exothermic reaction.
The chemical packs generally come in two varieties: the bag-in-bag type or the side-by-side type. The bag-in-bag type wrap has two separate bags, with a smaller bag containing one of the reactants included within the larger bag that contains the other reactant. Bag-in-bag chemical packs suffer from the significant disadvantage that there is a large surface area, represented by the exterior surface of the smaller bag, between the first reactant and the second reactant. Here, if a reactant is a liquid or gas, it will migrate through the plastic material of the smaller bag and into the second reactant causing a pre-activation intermixing of the reactants that results in a short shelf life and a lower efficiency upon intentional activation. This migration through the smaller bag can be slowed by using a thicker plastic material for the smaller bag; however, when a thicker smaller bag is utilized, it becomes more difficult to activate the pack when activation is desired. Also, with the bag-in-bag design, it is sometimes difficult to rupture the smaller bag. A number of prior art devices have utilized a rigid spike to facilitate rupturing the smaller bag. This presents significant shortcomings in that the rigid spike may puncture the larger bag in use or in shipping and handling causing external leaking.
The side-by-side bags utilize a breakable seal between two compartments located side-by-side, each compartment containing one of the reactants. These side-by-side packs attempt to utilize a strong seal around the perimeter of the bag and a weak seal to separate the two compartments. This is very difficult to do on a consistent basis and with known manufacturing techniques and leads to a situation where a force, intended to mix the two reactants, breaks an exterior seal causing a leak of the reactants onto the potential user.
As such, a need continues to exist for a hot or cold wrap or pack that is relatively easy to activate.